The present disclosure relates to a development device configured to develop an electrostatic latent image formed on an image carrier by using a one-component developer and to an image forming apparatus including the development device.
As a development device used in an image forming apparatus, such as printer, and configured to develop an electrostatic latent image formed on an image carrier by using magnetic one-component developer, a development device having a technique as mentioned below is known. Such a development device includes a developer carrier including a fixed magnet, a layer thickness adjusting member configured to adjust the thickness of a developer layer formed on the developer carrier, and a developer conveying member configured to supply the developer to the developer carrier.
According to the above-mentioned technique, the circumferential speed of the developer carrier is set to be higher than five times the circumferential speed of the developer conveying member in a position where the developer carrier and the developer conveying member faces to each other.
As the above-mentioned technique, in a case where the circumferential speed of the developer carrier is set to be higher than five times the circumferential speed of the developer conveying member, in other words, when the circumferential speed of the developer conveying member is set to be less than ⅕ of the circumferential speed of the developer carrier, the stress subjected to the developer is decreased. In this case, however, the supply of developer from the developer conveying member to the developer carrier was occasionally deficient.
In particular, in a case where the developer conveying member has a screw shape having a helical blade arranged around a rotation shaft, the supply amount of the developer is large in the helical blade portion and the supply amount of the developer is deficient in the rotation shaft portion. As a result, a partial difference in the amount of the developer occasionally often may occurs on the back side of the layer adjusting member, thereby causing a difference in density in the shape of a longitudinal streak on the image.
On the other hand, when the circumferential speed of the developer conveying member is significantly increased to supply a lot of the developer from the developer conveying member to the developer carrier, many developer is retained on the back side of the layer adjusting member. In this case, a problem arose in that deterioration of the developer is accelerated and the driving torque of the development device increases.